It's fun, it's goofy... it's scientific papers that probably shouldn't be published anywhere else! Here they are, for worldwide open discussion and peer review! Some of it is news... some of it is strange... we just report it!

Tuesday, December 05, 2006

Cubic Zirconia - What Is It?

Author: Liz Brodie

With the cost of diamonds soaring to record highs and the huge influence of 'bling' on today's fashion scene, Cubic Zirconia jewellery is seeing a huge rise in popularity. Cubic Zirconia is probably the closest man made material to the looks, hardness and feel of real diamond. But few people know what it is or how it's made so here's a brief summary for those interested...

Zirconium in its pure form is actually a chemical element that can be found in the periodic table. For those interested it has an Atomic Number of 40. However, although a naturally occurring element and metal, it is not found in its pure form and instead forms a part of several minerals, the most common being Zirconium Silicate which is mined heavily in the USA, Australia, India, Brazil and Russia.

Zirconium was discovered in 1789 by the German chemist Martin Klaproth, although he did not manage to isolate the element. This was achieved in 1824 by Jons Jakob Berzelius, a Swedish chemist, with pure Zirconium first prepared in 1914. Pure Zirconium is a greyish-white metal that is used in a wide range of industrial processes including heavy use by the Nuclear industry due to its hardness, heat resistance and non-reactive properties. These characteristics also help to make it ideal for jewellery.

Obviously a grey-white metal would hardly make an ideal substitute diamond so the raw material needs processing to produce the clarity required for jewellery. To do this high purity zirconium oxide powders, stabilized with magnesium and calcium, are heated to very high temperatures until they melt together, crystalising and clarifying on cooling to produce a clear, hard substance with properties similar to diamond and suitable for use in jewellery. During this process small amounts of other chemicals can also be added to produce different coloured crystals.

Although 'close' to real diamond, there are obviously small different between Cubic Zirconia and diamond including hardness and brilliance. The naked eye finds it hard to differentiate between the two, however true diamond does have an increased refractive index (the ability to refract a ray of light into its component colours). Cubic Zirconia (CZ) has a refractive index of around 2.16, whereas diamond has an index value of 2.42. As I say, although this is difficult to pickup with the naked eye it does mean that true diamond will always 'sparkle' just that little bit more when properly cut.

The hardness of the two materials is also different. As most people are aware, diamond is an incredibly hard material and often used for industrial cutting and grinding processes. In fact diamond tops the hardness scale with a value of 10 whereas CZ is a little lower at around 8.7.

Hardly exciting reading I know but the above at least gives a little insight in to where CZ comes from and why it remains so popular for Jewellery. At the end of the day it simply looks good and can be purchased without breaking the bank.

About the author: Liz Brodie owns and operates Silver Jewellery World, an online UK jewellery shop offering stunning designs at great prices including some great silver jewellery inset with quality Cubic Zirconia.